Fatigue behaviour of cast magnesium alloy AZ91 microstructurally modified by friction stir processing |
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| Authors: | Y. UEMATSU K. TOKAJI K. FUJIWARA Y. TOZAKI H. SHIBATA |
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| Affiliation: | Department of Mechanical and Systems Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan;, Honda Motor Co., Ltd, 2-1-1 Minamiaoyama, Minato-ku, Tokyo 107-8556, Japan;, Gifu Prefectural Research Institute for Machinery and Material, 1288 Oze, Seki 501-3265, Japan |
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| Abstract: | Friction stir processing (FSP) was applied to cast magnesium alloy AZ91-F to modify the as-cast microstructure, and the effect of FSP on fatigue behaviour was discussed based on microstructural consideration, crack initiation, crack growth behaviour, and fracture surface analysis. Fully reversed axial fatigue tests have been performed using as-cast, T5-aged and their FSPed specimens (as-cast/FSP and T5/FSP). It was found that both FSPed specimens exhibited significantly higher fatigue strength than the as-cast and T5-aged specimens. FSP resulted in the break-up of coarse as-cast microstructure, grain refinement of the matrix, finely dispersed precipitates and increase of hardness, thereby both the crack initiation resistance and the crack growth resistance were considerably enhanced compared with the as-cast and T5-aged specimens, resulting in the improved fatigue strengths of the FSPed specimens. |
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| Keywords: | cast magnesium alloy crack initiation fatigue behaviour friction stir processing microstructural modification small crack growth |
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